1. Special license plates are made up of 2 letters followed by 4 digits. How many can be made:
a) If all the letters are made of the same letter, while the digits can be any digit.
b) If all the digits are made of the same digit, while the letters can be any letter.
2. How many bit strings of length 8 can be made such that they begin with one zero and end with end with zero? Given a list of 5000, find out:
a) How many persons are at least born on the same day of the week?
b) How many persons are at least born on the same month?
3. The following represents the sequence; 3, 4, 6, 8, 9
a) How many numbers must be selected if at least three of the selected numbers must add up to 18
b) How many numbers must be selected if at least two of the selected numbers must add up to more than 10